FIG. 1 illustrates a prior art blower wheel comprising a blade strip assembly stamped from a continuous sheet of metal. The blade strip assembly permits a simplified manufacturing process for assembling the blower wheel, as compared to other types of blower wheels comprising separate, individual blades. The blade strip assembly is formed into a cylinder, and placed into a blower wheel assembly machine, wherein the cylinder is rotated while a ring is crimped to one end of the cylinder and a backplate is crimped to another end of the cylinder. A hub is furthermore attached to the backplate as a means for coupling the blower wheel to a shaft for rotation thereof.
The assembled blower wheel 100 comprises a plurality of blower wheel components 110, such as a ring 112, a blade strip cylinder 114, a backplate 116, and a hub 118. In the assembled blower wheel 100, the ring 112 is crimped onto a first end 120 of the blade strip cylinder 114, and the backplate 116 is crimped onto an opposing second end 122 of the blade strip cylinder while the blower wheel components 110 are rotated in a blower wheel assembly machine (not shown).
For clarity purposes, FIG. 2 more clearly illustrates the blower wheel 100 in an exploded view. A first flange 124 of the ring 112 is crimped onto the first end 120 of the blade strip cylinder 114, and a second flange 126 of the backplate 116 is crimped onto the second end 122 of the blade strip cylinder. In general, the ring 112 and the backplate 116 are crimped onto the cylindrical blade strip 114 while a machine rotates the blower wheel components 110 under moderate compression. The hub 118 is furthermore attached to the backplate 116 by deforming a lip 128 of the hub onto the backplate. This deformation typically is performed utilizing a pressing operation at a separate pressing machine, whereby the hub 118 is joined to the backplate 116.
FIG. 3 illustrates an exemplary prior art blower wheel assembly machine 150. The blower wheel assembly machine 150 comprises a base 152, whereon the blower wheel components 110 are placed for assembly. A motor 154 drives a shaft 155 attached to the base 152, thereby defining an axis 156, and resulting in a drive rotation RDRIVE of the shaft, base, and blower wheel components 110 about the axis. An actuator 157 applies a clamp 158 onto the blower wheel components 110 to radially and axially constrain the blower wheel components during assembly, thereby rotationally coupling the base 152 to the clamp 158 via the blower wheel components. The drive rotation RDRIVE is therefore transferred to the clamp 158 via the blower wheel components 110, thereby resulting in a driven rotation RDRIVEN of the clamp. During the rotation of the blower wheel components 110, one or more crimping assemblies 160 crimp the first flange 124 and the second flange 126 onto the blade strip cylinder 114, thereby generally attaching the ring 112 and the backplate 116 to the blade strip cylinder, respectively.
Coupling the base 152 to the clamp 158 via the blower wheel components 110, however, can cause a twisting of the blade strip cylinder 114 due to inertial forces from the clamp. Inertial forces from the clamp 158 and blower wheel components 110 must be overcome during both a start and a stop to the drive rotation RDRIVE. Since the driven rotation RDRIVEN of the clamp is driven via the blower wheel components 110, the rotational inertia of the clamp 158 and blower wheel components 110 may cause an inequality between the drive rotation RDRIVE and the driven rotation RDRIVEN, thereby causing an undesirable twisting of the blade strip cylinder 114.
In the industry, an emphasis has been placed on decreasing thicknesses of sheet metal used in the fabrication of the blade strip cylinder 114 to reduce material cost, as well as to decrease the overall weight of the blower wheel components 110. Furthermore, a discrepancy between the drive rotation RDRIVE rotation and the driven rotation RDRIVEN during starting and stopping of the rotation of the blower wheel components 110 will tend to increase when thinner sheet metals are utilized, thus increasing the undesirable effects of twisting the blade strip cylinder 114.
In the assembly of a blower wheel 100 of FIG. 1, a sturdy connection of the hub 118 to the backplate 116 is also necessary in order to avoid slippage of the backplate with respect to the hub during operation of the blower wheel, wherein the hub is attached to a rotating shaft (not shown). In the prior art, the hub 118 is typically pressed or deformed into the backplate 116 by a press as a separate operation to the assembly of the backplate and ring 112 to the blade strip cylinder 114. Operations at multiple assembly machines increases an amount of time required to produce the blower wheel 100, and increases a cost of the blower wheel.